Magick is all about the mind. You have probably performed magick throughout your life without ever knowing it. Ever had a "lucky" item that you swore by? Magick.
It doesn't take much to cause influence on the world around us, all it takes is the right mindset.
Did you change the weather? Perhaps. I think its better to assume so and build your confidence than to doubt it and create insecurity. You should always assume when casting that it will work and that the result was caused by your influence. It will indeed build your confidance and willpower, which will build your ability to influence. But always always remember, in magick we are not alone! Our guides, nature spirits, the elements themselves and other beings that we gain favor from will aid us in our work. So always give them thanks and respect. You may have effected the weather, or a spirit of nature may have just answered your silent prayer/desire.
Regardless, you are developing connections, and you will continue to.